Alain Karma College of Arts & Sciences Distinguished Professor PhD University of California at Santa Barbara, 1986 (617)373-2929 a.karma@neu.edu

Research Summary:

My main research interest lies in theoretical understanding of the emergence of nonequilibrium patterns in nonlinear systems with applications to diverse problems in materials science and biology that are both of fundamental and practical relevance. This research makes extensive uses of mathematical models and computational approaches rooted in nonequilibrium statistical physics and nonlinear dynamics.

In the materials arena, a main focus in my group has been the application of the phase-field method to microstructural pattern formation in alloys. A more recent focus is the extension of this method to stress driven processes leading to materials failure such as crack propagation and crystal decohesion. The phase-field method provides a powerful computational approach to describe the complex evolution of interfaces such as phase and grain boundaries that shape the microstructure of a material, and hence determine some of its key properties such as tensile strength and wear resistance. The power of this method rests on the spatiotemporal coarse-graining of atomistic details that renders continuum scale simulations of interface dynamics feasible. Much of the excitement in this line research has been generated by recent successes to combine atomistic and phase-field methods to make materials specific predictions on experimentally relevant length and time scales, which is becoming increasingly feasible due to the rapid advances in computer power. An ultimate practical goal of this research is to use computer simulations to optimize the properties of advanced materials.

In the biological arena, our efforts have focused on understanding basic mechanisms of "cardiac arrhythmias", a term commonly used to describe irregular heart rhythms. Of particular interest is ventricular fibrillation, a turbulent rhythm that stops the heart from pumping and is the leading cause of sudden death among industrialized nations. Ventricular fibrillation claims about 300,000 lives per year in the US. While high risk patients can carry implantable defibrillators, reducing mortality in the wider population of patients who die suddenly and unpredictably from ventricular fibrillation has remained a major challenge. Our recent studies have focused on elucidating the origin of spatiotemporal patterns of period doubling oscillations of calcium and voltage signals in cardiac cells and tissue (networks of cardiac cells) that make the heart susceptible to the onset of life-threatening arrhythmias and fibrillation. This research has the potential to improve current means to identify high risk patients and to prevent cardiac fibrillation beyond the limitations of current therapies, either pharmacologically, or using low amplitude electrical stimuli as an alternative to a massive defibrillatory shock.

Recent Selected Publications:

"Orientation Selection in Dendritic Evolution," T. Haxhimali, A. Karma, F. Gonzales, and M. Rappaz, Nature Materials 5, 660-664 (2006).

"Interface Mobility from Interface Random Walk," Z. T. Trautt, M. Upmanyu, and A. Karma, Science 314, 632-635 (2006).

"Turing Instability Mediated by Voltage and Calcium Diffusion in Paced Cardiac Cells," Y. Shiferaw and A. Karma, Proc. Nat. Acad. Sci. U.S.A. 103, 5670-5675 (2006).

"Control of Electrical Alternans in Canine Cardiac Purkinje Fibers," D. J. Christini, M. L. Riccio, C. A. Culianu, J. J. Fox, A. Karma, and R. F. Gilmour Jr., Phys. Rev. Lett. 96, 104101 (2006).

"Spatially Discordant Alternans in Cardiac Tissue: Role of Calcium Cycling," D. Sato, Y. Shiferaw, A. Garfinkel, J. N. Weiss, Z. Qu, and A. Karma, Circ. Res. 99, 520-527 (2006).

Recent Review Articles:

"Atomistic and Continuum Modeling of Dendrite Solidification," J. J. Hoyt, M. Asta, and A. Karma, Mat. Sci. Eng. R 41, 121-163 (2003).

"Phase Field Modeling," A. Karma, in Handbook of Materials Modeling. Volume I: Methods and Models, edited by S. Yip, Springer, Netherlands, pp. 2087-2103 (2005).

"Nonlinear Dynamics of Paced Cardiac Cells", Y. Shiferaw, A. Garfinkel, Z. Qu, and A. Karma," J. N. Weiss, Ann. N.Y. Acad. Sci. 1080, 376-394 (2006).

Links:

Complete Publication List

Condensed Matter Physics Publications

Biological Physics Publications